Caffeine

Ahhhh, caffeine, that incredible drug that makes millions of people drink coffee each day. It is a white, crystalline powder that has incredible powers. And as we all know, those powers are very stimulating!!! It also is a diuretic, which means unless you are exercising (exercising has been shown to counteract this effect) you are going to urinate more than usual. So, if you are drinking caffeinated beverages, be sure to drink lots of water, too!

All of these drinks are brewed... therefore, the caffeine content will vary greatly depending on how the drink is made.

This information was taken from (what was originally) Alejandro Lopez-Ortiz's Caffeine FAQ.

Health Risks

Many, many, many studies have been done on the physical effects of caffeine and coffee on the human body. To make a long story short, nearly all studies agree that there are no health-risking effects. However, there are a few studies that have shown some risks. Now, before you start worrying, let me finish. Most of these studies that suggest health risks were not configured for just caffeine and coffee. This means that other factors, like smoking, were not taken out of the picture. Therefore, most of these studies are not taken too seriously...

Decaffeinating

As we all know, there are two types of coffee drinkers in this world: those who drink it leaded, and those who drink it unleaded. For those of you who drink the unleaded kind, here is some information for you. As of now, there are no health risks involved with decaf coffee, no matter what decaffeinating process is used. As for the difference in flavor, well, that seems to be a personal judgment. Caffeine does have a bitter flavor which undoubtedly lends itself to a cup of coffee. However, most people I know cannot tell any taste difference between caf and decaf. I suspect, however, that a true connoisseur/snob can taste the difference...
There are two major methods for decaffeinating coffee: In the direct method, the caffeine-removing agent is treated directly to the beans. First, the green (unroasted) beans are steamed to loosen them up. Then, a solvent treats the beans to extract the caffeine, a process which takes about 10 hours. After this, the beans are steamed again, this time for 8-12 hours. This is done to not only rinse the beans of the solvent, but to help the solvent evaporate. Finally, the beans are dried using air or vacuum dryers. In this method, the possible solvents to be used are methylene chloride, triglycerides (obtained from spent coffee grounds), and carbon dioxide.
In the indirect method, the caffeine-removing agent is treated with the solution that contains the caffeine. The first step in this method is to soak the green beans in near boiling water for several hours to get the caffeine out of the beans. This soaking also takes with it other chemicals from the beans which lend themselves to the flavor. After this, the solution is separated from the beans where it is then treated with a solvent which will remove just the caffeine. After the caffeine and solvent are removed from the water-based solution, the solution is returned to the beans in order that the lost chemicals can be reabsorbed by the beans. The possible solvents for this process are methylene chloride, ethyl acetate, and carbon.
As for the caffeine that is removed, it goes on to another life. It is sold to pharmaceutical companies and cola companies so that it can still be used to keep people awake! Now caffeine is all over the place. It's even in water and breath mints!
*This information was republished from Stairway to Coffee